The related art illuminating apparatuses include, for example, illuminating apparatuses shown in FIGS. 10 to 12.
The illuminating apparatus shown in FIG. 10 is provided with a pointer 52 adapted to be turned around a rotary shaft 51, a dial 53 constituting a display member positioned at the rear side (lower side in the drawing) of this pointer 52 and transmission illuminated, a hard circuit board 54 positioned at the rear side (lower side in the drawing) of this dial 53 and formed of a glass epoxy resin, light-emitting diodes 55, 56 provided on this circuit board 54 and serving as light sources for illuminating the pointer 52 and dial 53 respectively, a cylindrical partition 57 defining regions to be illuminated by the light-emitting diodes 55, 56 respectively, and a meter body 58 fixed to the rear side (lower side in the drawing) of the circuit board 54 and adapted to turn the rotary shaft 51.
In the point r 52, an indicating member 59 and a pointer base portion 60 fixed to the rotary shaft 51 are formed in on body out of a transparent synthetic resin, and the pointer base portion 60 is covered with a pointer cap 61 made of a light shielding synthetic resin. The indicating member 59 receives the light from the light-emitting diodes 55 and emits the light.
The dial 53 is formed of a flat base material 62 of a transparent synthetic resin, which is provided on an outer surface (upper surface in the drawing) thereof except index portions 63 having a graduation, letters and the like with a light shielding layer 64 of a black light shielding coating material forming a ground of the dial 53, and on a rear surface (lower surface in the drawing) thereof except the index portion 63 having the graduation, letters and the like with a light shielding reflecting layer 65 of a white light shielding coating material. Therefore, this illuminating apparatus has a structure in which the index portions only 63 are transmission illuminated.
The light-emitting diodes 55, 56 are surface mounting type light-emitting diodes, and the light-emitting diodes 55 are provided plurally along an imaginary circle in the vicinity of and extending around and coaxially with the rotary shaft 51. The light-emitting diodes 56 are provided plurally on a circle around the rotary shaft 51 on the portion of the circuit board which is just under the index portions 63. The partition 57 is made of a synthetic resin, and adapted to define regions to be illuminated, in such a manner that the rays of light sent out from the diodes 55, 56 are not mixed with one another.
This related art example is formed so that the index portions 63 are transmission illuminated directly by the light-emitting diodes 56 positioned just thereunder.
Since this illuminating apparatus is formed so that the index portions 63 are transmission illuminated by the light-emitting diodes 56, it is difficult that the number of the light-emitting diodes 56 be reduced for the purpose of preventing the unevenness of the transmission illumination of the index portions 63 from occurring. Therefore, there is a limit to the reduction of the manufacturing cost. Since the index portions 63 are usually provided in a circumferential portion of the dial 53, it is necessary that the light-emitting diodes 56 opposed to the index portions 63 be also away from the pointer illuminating diodes 55. This causes a pattern (not shown) of conductors provided on the circuit board 54 to become complicated, and renders the designing of the illuminating apparatus difficult.
Other related art illuminating apparatuses designed so as to eliminate these inconveniences include the illuminating apparatus shown in FIG. 11. In this drawing, the portions identical with or corresponding to those in the previously-described related art illuminating apparatus will be designated by the same reference numerals and a detailed description thereof will be omitted.
The related art illuminating apparatus of FIG. 11 is provided with light-emitting diodes 56 provided in the vicinity of a partition 57, a reflecting wall 66 formed on the partition 57, and a reflector 67 positioned on a rear surface of a dial 53 just under, especially, index portions 63.
The light-emitting diodes 56 are provided plurally on a circle in the vicinity of the and partition 57 extending around a rotary shaft 51.
The reflecting wall 66 is made integral with the partition 57, and positioned above the light-emitting diodes 56. The reflecting wall 66 is conically shaped, and adapted to reflect the light, which is sent out from the light-emitting diodes 56, radially with respect to the rotary shaft 51 as the center toward the reflector 67.
The reflector 67 is made of a synthetic resin, and a reflecting surface 68 thereof has a curved cross-sectional shape so as to have the light, which has been reflected on the reflecting wall 66, reflected excellently on a rear surface of a dial 53.
This related art example is formed so that the light from the light-emitting diodes 56 is reflection diffused at the reflecting wall 66 and reflecting surface 68 or at a circuit board 54, partition 57, a light shielding reflecting layer 65, reflecting wall 66 and a reflecting surface 68 to transmission illuminate index portions 63.
This illuminating apparatus has a loss of the quantity of light, and the reduction of the number of the light sources is not expected much since the luminance of the index portions 63 has to be secured, the reduction of the manufacturing cost being thereby limited.
Still other related art illuminating apparatuses designed so as to eliminate these inconveniences include an illuminating apparatus shown in FIG. 12. In this drawing, the portions identical with or corresponding to those of each of the previously-described related art illuminating apparatuses will be designated by the same reference numerals, and the detailed description thereof will be omitted.
This related art example is provided with a light guide member 69 positioned between a dial 53 and a circuit board 54 and adapted to guide the light sent out from light-emitting diodes 56 to index portions 63, and a white synthetic resin case 70 supporting this light guide member 69.
The light guide member 69 is a part for guiding the light from the light-emitting diodes 56 to the index portions 63, and adapted to receive the light at a light receiving portion 71 and reflect the light which has passed through the interior of the light guide member 69 on a reflecting surface 72, the reflected light being guided to the rear side of the dial 53 which corresponds to the index portions 63 to transmission illuminate the index portions 63. The reflecting surface 72 is provided with a whit print layer (not shown) so as to excellently reflection diffuse the light and guide the resultant light to the index portions 63. When the light guide member 69 is thus used, the index portions 63 can be transmission illuminated without causing a loss of the quantity of light to occur until the light reaches the index portions.
The light guide member 69 is provided with a locking claw 73, while the case 70 is provided with a hole 74 opposed to the locking claw 73. The light guide member 69 is fixed to the case 70 by inserting the locking claw 73 through the hole 74 and engaging the locking claw with a rear surface of the case 70.
However, since a large light guide member 69 is needed in this illuminating apparatus, the weight of the apparatus increases. Since the light cannot be excellently reflection diffused at the reflecting surface 72 of the light guide member 69 toward the index portions 63, the white print layer mentioned above is provided thereon. In order to form the white print layer on the reflecting layer, inexpensive screen printing cannot be utilized since the light guide member 69 is provided with a projection, such as the light receiving portion 71, etc. Therefore, an expensive hot stamp has to be used, and this causes the manufacturing cost to increase.
The present invention has been mad in view of these circumstances, and provides an inexpensive illuminating apparatus capable of excellently illuminating object members by efficiently guiding the light from light sources thereto.